Technical Review: Neural Recording Circuits for Bidirectional Neural Interface

A variety of neurological therapeutic devices and brain machine interface applications have increased the need of closed-loop neuromodulation systems. The closed-loop system requires a bidirectional neural interface which can perform both recording and stimulation functions. In such a system, large artifacts caused by high-voltage stimulation strongly interfere the recording operation, which needs to acquire very weak neural signals. As a result, the dynamic range, or the span of the signal magnitude that can be read out by the recording circuit has become one of most important performance parameters. In this paper, state-of-the-art designs for low-power high-performance neural recording circuits are reviewed with an emphasis on the circuit techniques employed for achieving large dynamic range. Various recent circuit topologies and design approaches are compared with describing their advantages and disadvantages.